Participants will have cancer metastases to the brain which are not treatable with surgery, but may be partially treated with radiation therapy. Because of this, the patient is being invited to participate in this research study. Gadolinium is a contrast agent that is used to improve certain types of X-rays, such as MRI and CT images. Texaphyrins are substances which attach to liver and cancer tissues. When gadolinium and texaphyrin are combined into one drug, they may enhance MRI images of tumors and increase the sensitivity of tumors to radiation therapy. There has been one previous study using PCI-0120 in patients with metastatic cancer. The study is ongoing. Some subjects in this study have brain metastases. That was the first time PCI-0120 was given to humans. The purpose of this research study is to evaluate the safety, effectiveness, and maximum tolerated dose of an investigational drug called Gadolinium Texaphyrin (PCI-0120).